Information, work, and heat in small systems

大约150年前，詹姆斯·克雷克·麦克斯韦尔第一次问道，当“手指灵巧的生物”--恶魔--利用信息从热量中提取有用的能量(功)时，会发生什么。热力学第二定律应该禁止这种情况，但如何做到呢？这个问题激怒了物理学家，并引发了长达一个多世纪的争论。从2008年开始，我的实验室开发了一种新技术来创造和研究这样的麦克斯韦恶魔和相关设备，以收集和使用相关信息。这种反馈陷阱让我们可以将一个微米级的小珠子放在一个潜在的位置上，我们基本上可以随意设计它的形状。这一技术进步在热力学、非平衡统计物理、信息论和控制论的交叉领域带来了重要的科学应用，特别是2014年的一项最终测量，证实了一个已有60年历史的假设：麦克斯韦恶魔需要擦除信息，擦除信息需要消耗所获得的能量。在接下来的五年里，我的研究计划将集中在三组项目上：1.异常冷却和供暖。我们最近使用我们的反馈陷阱来证明，在相同的条件下，热系统有时可以比热系统冷却得更快(“Mpemba效应”)。在这一成功的基础上，我们将研究最近提出的反常加热情景(逆Mpemba效应)和相关问题。2.信息和热力学实验。我们将继续信息引擎方面的工作，总体目标是将麦克斯韦恶魔从提出悖论的思维实验转变为基本热力学极限的实验演示，再到执行有用任务的实际设备。我们将优化在有限速率下运行的基本计算操作(比特擦除、逻辑门)的成本，并研究信息发挥作用的新问题，例如稳定不稳定系统所需的最低功率。3.单室内的热流。我们将开发新的仪器来研究单个生物细胞的产热。更长期的动机是创造一种新的工具来了解细胞新陈代谢的动态--营养是如何在单细胞水平上被消耗的。短期目标是解决一个显著的科学差异，即预测的细胞内温度变化和测量的细胞内温度变化之间的“105差距”。前两个项目直接扩展了之前在我的团队中的工作(非常成功)。第三个是一个新的方向，有可能创造一个新的领域(单细胞测热法)，并解决我们这个时代的一个突出的科学难题。上述问题奠定了我们对生物学、生命以及小规模工程学的理解。他们将在加拿大和其他地方激励和帮助培训新一代HQP。

Nearly 150 years ago, James Clerk Maxwell first asked what happens when a "neat-fingered being"-a demon-takes advantage of information to extract useful energy (work) from heat. The Second Law of Thermodynamics should forbid this, but how? The question galled physicists and provoked debate for well over a century. Starting in 2008, my lab developed a new technique for creating and studying such Maxwell demons and related devices for gathering and using relevant information. This feedback trap lets us place a small, micron-scale bead in a potential whose form we can design, essentially at will. This technological advance has led to important scientific applications at the intersection of thermodynamics, nonequilibrium statistical physics, information theory, and control theory, notably a definitive measurement in 2014 that confirms a 60-year-old hypothesis: that Maxwell demons need to erase information and that erasing information requires dissipating as much energy as is gained. The next five years for my research program will focus on three groups of projects: 1. Anomalous cooling and heating.  We recently used our feedback trap to show that a hot system can sometimes cool more quickly than a warm system under identical conditions ("Mpemba effect"). Building on this success, we will investigate a recently proposed anomalous-heating scenario (inverse Mpemba effect) and related questions. 2. Experiments on information and thermodynamics.  We will continue work on information engines, with the overall goal of transforming Maxwell demons from thought experiments raising paradoxes to experimental illustrations of fundamental thermodynamic limits to practical devices that carry out useful tasks. We will optimize the costs of basic computational operations (bit erasure, logic gates) when operated at finite rates and look at new problems where information plays a role, such as the minimum power needed to stabilize an unstable system. 3. Heat flow in single cells.   We will develop new instrumentation for studying heat production from single biological cells. The longer-term motivation is to create a new tool for understanding the dynamics of cellular metabolism-how nutrients are consumed at the single-cell level. The shorter-term goal is to resolve a striking scientific discrepancy, the "105 gap" between predicted and measured intracellular temperature variations. The first two projects directly extend previous (very successful) work in my group. The third is a new direction, with the potential to create a new field (single-cell calorimetry) and resolve one of the outstanding scientific puzzles of our time. The above questions are ones that underlie our understanding of biology and life, as well as engineering at small scales. They will inspire and help train a new generation of HQP, in Canada and beyond.